A method of wellbore analysis using TM01 and TE01 modes of radar waveforms can include transmitting, at a first time, a radar waveform from a wellhead into a tubing disposed in a wellbore positioned in a reservoir. The radar waveform is either a TM01 mode or a TE01 mode waveform. The tubing includes a fluid, and the surface of the wellbore includes the wellhead. At a second time, a reflected waveform generated by reflecting the transmitted radar waveform on a fluid surface of the fluid is received at the wellhead. A fluid level of the fluid is determined based on the time difference between the first time and the second time, and on a transmission speed of the radar waveform from the wellhead to the fluid surface. The fluid level is a distance between the wellhead and the fluid surface of the fluid.